/*
//alert(3);

//alert(woDeMingZi);
//alert(myTeacherAge);
var woDeMingZi

//myTeacherAge
woDeMingZi = 'Mr.Liu'
myTeacherAge = 10

console.log(woDeMingZi);
console.log(myTeacherAge);

console.log("---------------------")
delete woDeMingZi;
delete myTeacherAge;

console.log(woDeMingZi);
//console.log(myTeacherAge);

//mess;
//mess = 100;
//console.log(mess);

function test(){
    var info = 123;
    console.log(info);
}
test();
//console.log(info);

var index = 10;
if( index > 5){
    let ctx = "hello";
    console.log(ctx);
}
//console.log(ctx);
*/
/*
if(undefined == null){
    console.log("一样1")
}
if(undefined == undefined){
    console.log("一样2")
}
if(null == null){
    console.log("一样3")
}
var n1;
var n2;
if(n1 == n2){
    console.log("一样4")
}
*/
/*
var n1 = 'abc';
var n2 = "abc";
if(n1 === n2){
    console.log('一样5');
}

var n3 = '100';
alert(typeof(n3))
var n4 = n3;

var num1 = 10;
var num2 = 5;
var num3 = (num1 + num2) / 5;
//num1++;
--num1;
alert(num1);
*/

/*
var n1 =10;
n1 += 5; //等同于 n1=n1+5;
alert(n1);
*/
/*
var n1 =10;
var n2 = ++n1;
var n3 = 15;
//console.log(n1,n2);

//console.log(n1 > n2)
console.log(n1 == n2)
console.log(n1 === n2)

if(n1 < n3 && n2 > n3){
    console.log("两个都为true")
}
//    true ||    false && false
if(n1 < n3 || n2 > n3  && n1 < n2){
    console.log("至少有一个为true")
}
if(!(n2 > n3)){
    console.log("333")
}

var n4 = 1;
if(n4){
    console.log("进来了")
}
*/
/*
var n1 = 1;
var n2 = 2;
var n3 = 3;
var n4 = n1+n2+++n3;
console.log(n4,n2);
*/
// alert("弹出对话框");
// document.writeln('往页面显示文本<br/>')
// document.write('往页面显示文本')

// console.log('控制台');

// var n1 = parseInt(prompt("请输入数字：",'数字'));
// var n2 = parseInt(prompt("请输入数字：",'数字'));
// var n3 = parseInt(n1)+parseInt(n2);
// //var n3 = n1 + n2;
// console.log(n3)

var n1 = parseInt(3.94);
console.log(n1);
var n2 = parseFloat(5.1);
console.log(n2);
console.log(typeof(n2))
let abc;
if(true){
    abc = 123;
}
abc